Khattara, A., W. R. Cherif-Khettaf, and M. Mostefai. “RETRACTED: An Efficient Metaheuristic Approach for the Multi-Period Technician Routing and Scheduling Problem”. Engineering, Technology & Applied Science Research, vol. 9, no. 5, Oct. 2019, pp. 4718-23, doi:10.48084/etasr.3091.